Abstract 612: Differential Expression of the Estrogen Receptors GPR30 and ERa in the Kidney of the Diabetic Hypertensive mRen2.Lewis Strain

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Diabetes was induced in adult female and male mRen2.Lewis rats at 11 wk of age with a single dose of streptozotocin (STZ at 65mg/kg ip) dissolved in 0.1 M citrate buffer (diabetic); the control group received a single dose of 0.1 M citrate buffer pH 4.5 (nondiabetic). The rats were followed for 4 weeks without insulin replacement. Kidney cortex was lysed and centrifuged at 100,000g to generate cytosolic and membrane fractions. The cortical fractions were probed with antibodies to the Receptor levels for GPR30 in the membrane fractions and ER-α in both membrane and cytosolic fractions were quantified by protein immunoblot. Following detection, membranes were reprobed with mouse monoclonal anti-β-actin (1:5,000; Sigma) as a loading control, and bands were quantified by MCID densitometry software. All measurements are expressed as means ± SE. An unpaired Student’s t-test compared GPR30 and ER-α protein expression between the control and diabetic group as well as females and males groups in both cytosol and membranes fractions. The expression of GPR30 tended to be higher in both the intact female [0.40 ± 0.17 vs. 1.04 ± 0.29] and the male [0.32 ± 0.18 vs 0.61 ± 0.13] diabetic mRen2.Lewis rats. and increased in both diabetic females and males GPR30 showed higher levels in control females than males [1.21 ± 0.49 vs 0.76 ± 0.39]; however, it decreased in diabetic females compared to males [0.79 ± 0.27 vs 1.03 ± 0.27]. Moreover, the ER-α receptor in the cytosolic fraction was lower in the diabetics females [3.68 ± 1.30 vs 1.36 ± 0.27], but remained unchanged in males [2.09 ± 0.23 vs 2.33 ± 0.39]. The same happened in the membrane fractions where there was not difference between controls and diabetics males [0.73 ± 0.16 vs 0.63 ± 0.40] while in diabetic females the ER-α receptor levels increased [0.97 ± 0.17 vs 1.27 ± 0.06]. Cortical content of ER-α in the cytosol was significantly increased in control females compared to control males [1.06 ± 0.14 vs 0.47 ± 0.04; p = 0.007], although it remained unchanged between diabetic females and males [1.26 ± 0.24 vs 1.44 ± 0.62].

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